Abstract: Objective: To investigate the expression of CD133,a cancer stem cell marker,in infiltrating ductal carcinoma(IDC) and its relationship with microvessel density( MVD) and clinical significance. Methods: The CD133 expressions in 105 specimens of IDC and 20 specimens of normal breast tissue and MVD count were detected by immunohistochemical ElivisionTM plus method. Results: The positive rates of CD133 expression in IDC and normal breast tissue were 5. 0% and 60. 0%,respectively,the difference of which had statistical significance( P 0. 01). The CD133 expression level differences in tumor differentiation,lymph node metastasis and clinical stage had statistical significance( P 0. 01). The MVD count differences in lymph node metastasis and clinical stage had statistical significance( P 0. 01 and P 0. 05),the difference of MVD count in the positive and negative specimens of CD133 expression had statistical significance( P 0. 01). Conclusions: The CD133 expression and MVD count are related to tumor lymph node metastasis and clinical stage. The joint detection of CD133 and MVD have important significance in predicting the progress and prognosis of IDC.